Apparatus for twisting wave form wire springs

ABSTRACT

The twisting apparatus comprises a transfer mechanism for transferring a formed wire spring to a working station and a pair of twisting units disposed on the opposite sides of the working station. Each unit comprises a mechanism for clamping the formed wire spring and a mechanism for twisting the formed wire spring while it is clamped between the clamping mechanisms. These mechanisms are actuated by pneumatic actuators. Means are provided for respective units for varying the twisting angle. The twisting units are also adjustable to vary the twisted portions of the formed wire spring.

United States Patent [1 1 Yoshimura 1 Mar. 25, 1975 APPARATUS FOR TWISTING WAVE FORM WIRE SPRINGS [75] Inventor: Shigeru Yoshimura, Hiroshima,

Japan [73] Assignee: NHK Spring Co., Ltd.,

Yokohama-shi, Japan 22 Filed: Feb. 27, 1974 21 Appl. No.: 446,276

[52] US. Cl. 140/71 R, 74/8917 [51] Int. Cl B21i 35/04 [58] Field of Search 140/71; 74/8917 [56] References Cited UNITED STATES PATENTS 3,022,804 2/1962 Corp 140/71 3,141,481 7/1964 Gonia et a1. 140/71 3,256,915 6/1966 Fisher, Jr. et a1 140/71 3,356,110 12/1967 Tuit ..140/71 Primary Examiner-Lowe1l A. Larson Attorney, Agent, or F z'rmF1ynn & F rishauf ABSTRACT The twisting apparatus comprises a transfer mechanism for transferring a formed wire spring to a working station and a pair of twisting units disposed on the opposite sides of the working station. Each unit comprises a mechanism for clamping the formed wire spring and a mechanism for twisting the formed wire spring while it is clamped between the clamping mechanisms. These mechanisms are actuated by pneumatic actuators. Means are provided for respective units for varying the twisting angle. The twisting units are also adjustable to vary the twisted portions of the formed wire spring.

5 Claims, 9 Drawing Figures APPARATUS FOR TWISTING WAVE FORM WIRE SPRINGS This invention relates to twisting apparatus for twisting a corrugated wire spring to produce a so-called formed wire spring such as a zig-zag shaped wire spring.

Wire springs twisted by such twisting apparatus are combined with springs of another type to form cushion frames for use in the seats of motor car or'the like vehicles, or sofas or beds.

In the prior art twisting apparatus a cam has been used to drive a twisting mechanism for twisting formed wire springs. In these prior mechanisms it is difficult to adjust the twisting angle of the formed wire springs and for the purpose of adjusting the twisting angle it is necessary to exchange the cam. For this reason, it takes a long preparation time before starting the twisting operation, thus decreasing .the efficiency of the operation.

Furthermore, in prior artapparatus in which several spaced portions of a formed wire spring :are twisted, a plurality of holding mechanisms for clamping the wire spring and a plurality of twisting mechanisms are secured to the base of the twistingapparatus at respective twisting positions. Thus, such apparatus is of the exclusive type wherein it is impossible to move the holding mechanisms and the twisting mechanisms to any desired positions to vary the twisting positions. In other words, such twisting apparatus can be used to prepare only products of a particular type so that it is necessary to install a plurality of apparatus of different types in order to obtain products of different types.

In addition, the prior apparatus is bulky, complicated in construction and expensive to manufacture.

SUMMARY OF THE INVENTION Accordingly, it is a general object ofthis invention to provide improved apparatus for twisting formed wire springs which can eliminate various defects of the prior art twisting apparatus.

According to this invention, a holding mechanism and a twisting mechanism at each twisting position or station are combined into a pair of upper and lower units acting as a twisting member, and each unit is constructed to be readily movable with respect to the main body of the apparatus.

Further, in accordance with this invention, the means for driving a respective twisting mechanism comprises a pneumatic cylinder instead of a cam and the twisting angle imparted to the formed wire spring by the twisting mechanism can be readily adjusted. More particularly, in a preferred embodiment the twisting mechanism is comprised by a rack and a pinion cooperating therewith and the stroke of the rack is varied by means of an adjustable lock nut thereby adjusting the twisting angle. In another embodiment, the stroke of the rack is varied by means of replaceable gauges of different sizes for the purpose of adjusting the twisting angle. Accordingly, the adjustment of the twisting angle can be made extremely readily and rapidly thus decreasing the preparation time before starting the twisting operation.

Thus, it is an object of this invention to provide a twisting apparatus capable of decreasing the preparation time and hence improving the operational efficiency.

A further object of this invention is to provide im proved twisting apparatus having a simple and compact construction and which can be manufactured at a low cost.

A still further object of this invention is to provide universal twisting apparatus capable of manufacturing twisted formed wire springs of various types.

Another object of this invention is to provide improved twisting apparatus capable of readily and rap idly varying the twisting angle of the formed wire springs.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantagesof the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1(a) and (b) show different types of formed wire springs that can be twisted by the twisting apparatus embodying the invention;

FIG. 2 is a diagrammatic general view, partly broken away, of the twisting apparatus constructed in apparatus with the teaching of the invention;

FIGS. 3(a) and 3(1)) are diagrams showing the steps of twisting a formed wire spring of one type by the twisting apparatus of this invention;

FIG. 4 is a diagrammatic representation of a completed'formed wire spring showing the order of twisting a formed wire spring;

FIG. 5 is an enlarged view of the transfer mechanism utilized in the twisting apparatus shown FIG. 2;

FIG. 6 is an enlarged sectional view of a modified means for adjusting the twisting angle utilized in the twisting mechanism of the twisting apparatus shown in FIG:2; and

FIG. 7 is an enlarged sectional view taken along a line 7--7 in FIG. 6.

DETAILED DESCRIPTION Referring now to the accompanying drawings, a formed wire spring 1 illustrated in FIG. 1(a) comprises a series of loop portions 2 and straight torque bar portions 3 interconnecting the corresponding ends of the loop portions. Portions 2 and 3 are alternately connected to form a zig-Zag shaped wire spring. A modified formed wire spring 4 illustrated in FIG. 1(b) comprises a series of horizontal spacer bar portions 5 and torque bar portions 6 which are alternately interconnected to form an irregular shaped formed wire spring. Although portions of the wire spring 4 take the form of a saw tooth, it is intended that such an irregular shaped formed wire spring is also included in the scope of this invention.

When such wavy wire springs l and 4 are twisted, the torque bar portions 3 and 6 are also twisted. There will now be further described the example of this invention where the torque bar portions of 3 of the zigzag shaped wire spring are twisted to bent the spring at a definite angle.

The twisting apparatus generally shown in FIG. 2 comprises a transfer mechanism 7 which operates to transfer a formed wire spring 1 to the working station A shown by two dots and dash line circle. The transfer mechanism 7 comprises an inclined chute 8, a dropping chute 9 and a vertical guide way 10 interconnecting both chutes 8 and 9. These chutes 8 and 9 guide way 10 are defined between a pair of vertically aligned guide plates 11 and 12. Actually, although two pairs of guide plates 11 and 12 are spaced apart a predetermined distance and the formed wire springs I extend between the two pairs, only one pair is shown in FIG. 2. The formed wire springs 1 are supported in chutes 8 and 9 and guide way 10 at their loop portions 2, so that the sections of springs 1 shown in FIG. 2 are those at the central portions of the loop portions 2.

A push up rod 13 is inserted through the guide way 10 to be movable in the vertical direction and a cam follower 13a larger than the width of the guide way 10 is mounted on the lower end of the push up rod 13 in a stopped opening 14 of the guide plate 11. A coil spring 15 is interposed between the cam follower 13a and the upper wall of the opening 14 for normally biasing the push up rod 13 toward lower.

A cam lever 16 pivotally mounted on a pin 17 is disposed in the opening 14 to cooperate with the cam follower l3a, and the lower side of the cam lever 16 is engaged by a spring feeding member 18. Member 18 has a sufficiently large width in the direction perpendicular to the sheet of drawing and a permanent magnet 19 is secured to the front surface for attracting the formed wire spring 1. The spring feeding member 18 is reciprocated on a base 20 by a pneumatic actuator comprising a piston 22, a piston rod 21 interconnecting the spring feeding member 18 and piston 22 and a cylinder 23. In FIG. 2, the member 18 is shown in its retracted position at which cam lever 16 is maintained in the horizontal position for maintaining the push up rod 13 in its raised position. Under these conditions, the inclined upper end of the push up rod 13 forms an extension of the dropping chute 9 and the upper end of the push up rod 13 closes the lower end of the inclined chute 8, thus arresting the lowermost one of the formed wire springs 1 contained in the chute 8.

A ledge 11a is projected beyond the discharge end 9a of the dropping chute 9 and above ledge 11a is provided a lever 24 hinged to the guide plate 12 for normally closing the discharge end 9a, thus stopping the formed wire spring 1 which has been dropped through the chute 9.

A pair of twisting units 25 and 26 having the same construction are disposed above and below the working station A. These units are mounted on four parallel stationary guide rails 27 by mounting blocks 28 so as to be movable along the guide rails. After the units have been moved to any desired working station, they are securely fastened to the guide rails 27.

Respective twisting units 25 and 26 comprise U shaped base blocks 29 and 30 including spindles 31 and 32, respectively, which are supported to be rotatable about their axes and to be movable in the vertical direction. At their intermediate portions, these spindles 31 and 32 are formed with pinions 31a and 32a, respectively, and bifurcated jaws 33 and 34 which cooperate with each other to clamp therebetween a formed wire spring 1 are mounted on their opposed inner ends. The spindles 31 and 32 are reciprocated by pneumatic actuators between their retracted positions shown in FIG. 2 and advanced positions at which they clamp a formed wire spring 1 at the working station A. The pneumatic actuators respectively comprise pistons 35 and 36 supported by pedestals 41 and 42, pistons 39 and in the cylinders and piston rods 37 and 38 respectively interconnecting pistons 39 and 40 and spindles 31 and 32. When pressurized air is admitted into cylinders 35 and 36 jaws 33 and 34 are advanced to clamp therebetween one formed wire spring 1. Thus jaws 33, 34, spindles 31, 32 and the pneumatic actuators constitute a spring holding mechanism.

Pinions 31a and 32a are disposed to mesh racks 43 and 44, respectively, extending at right angles with respect to the axes thereof and reciprocated by pneumatic actuators mounted on the righthand ends of the blocks 29 and 30. The pneumatic actuators comprise cylinders 45 and 46 secured to blocks 29 and 30, respectively, pistons 49 and 50 contained in the cylinders 45 and 46 and piston rods 47 and 48 respectively interconnecting pistons 49 and 50 and racks 43 and 44. When pressurized air is admitted into the cylinders 45 and 46 jaws 33 and 34 are rotated through racks 43 and 44 and pinions 31a and 32a whereby the formed wire spring 1 held between the jaws 33 and 34 will be twisted. Thus, racks 43, 44, pinions 31a, 32a and pneumatic actuators constitute a twisting mechanism for the formed wire springs.

To the lefthand ends of racks 43 and 44 are secured threaded rods 51 and 52 with their opposite ends projected outwardly through the vertical walls 29a and 30a of the U shaped blocks 29 and 30, respectively. Two pairs of lock nuts 53, 55 and 54, 56 are mounted on threaded rods 51 and 52 on the opposite sides of the vertical walls 29a and 30a, respectively. When engaged with the outer surfaces of the vertical walls 29a and 30a lock nuts 53 and 54 determine the right most positions of racks 43 and 44 whereas lock nuts 55 and 56 determine the left most positions of the racks 43, 44 by engaging the inner surfaces of the vertical walls 29a and 30a. Thus, the strokes of the racks 43, 44 are determined by these lock nut pairs. In FIG. 2, lock nuts 53 and 54 are shown in engagement with the outer surfaces of the vertical walls 29a and 300. In other words, under these conditions, racks 43 and 44 are in their right most positions or retracted positions. The meshing relation between the racks and pinions is selected such that the jaws 33 and 34 are in such relative angular position that they will positively clamp a formed wire spring 1 when they are advanced to the working station A. On the other hand, lock nuts 55 and 56 determine the left most positions of the racks 43 and 44, which positions are variable by adjusting these lock nuts 55 and 56 along threaded rods 51 and 52. In other words, variation in the strokes of the racks 43 and 44 results in corresponding variations in the twisting angles of the formed wire springs. Of course, lock nuts 53 and 54 that determine the retracted positions of the racks 43 and 44 may be made adjustable so as to correctly determine the retracted positions.

In this manner by varying the strokes of the racks 43 and 44 by adjusting the lock nuts 55 and 56 it is possible to adjust the twisting angle of the formed wire springs.

FIGS. 6 and 7 illustrate a modified mechanism for adjusting the twisting angle. In FIG. 6 is illustrated an upper twisting unit corresponding to unit 25 shown in FIG. 2 and is incorporated with such modified mechanism, and the elements corresponding to those shown in FIG. 2 are designated by the same reference numerals.

Different from the construction shown in FIG. 2, in the modified construction shown in FIG. 6, a rod 51 connected to one end 43a of the rack 43 is not provided with screw threads and is provided with an enlarged head 51a at its outer end projecting outwardly through the vertical wall 29a. An adjusting guage 57 is mounted on the rod 51 between the inner side of the vertical wall 29a and the end 43a of the rack 43. A plurality of gauges 57 having different width t are prepared and one of them is selectively used. Thus, the retracted position of the rack 43 is determined by the engagement of the head 51a against the vertical wall 2% whereas the advanced position shown by two dots and dash lines is determined by the engagement of the rack end 43a against the gauge 57. In this manner, the stroke of the rack 43 and hence the twisting angle of the formed wire spring 1 are determined by the width t of the gauge 57.

As shown in FIG. 7, the gauge 57 comprises a pair of arcuate halves 58 and 59 which are hinged together by a hinge 60 at theirupper ends. Although notshown in the drawing, a suitable spring is associated with the hinge 60 for normally biasing the halves 58 and 59 to the closed condition as shown in FIG. 7, so that it is possible to dismount the gauge 57 by spreading outwardly the halves 58 and 59.

The selective use of such gauges 57 permits ready and accurate adjustment of the twisting angle of the formed wire spring 1. In the actual operation of the twisting apparatus, since the adjustment of the twisting angle is not made so frequently, exchange of the gauge 57 does not result in any serious trouble.

The twisting apparatus of this invention described above operates as follows:

When the spring feeding member of the transfer mechanism is moved in the direction of X (see FIG. 5) by the pneumatic actuator, the cam lever 16 is carried to rotate in the clockwise direction from the raised position shown by two dots and dash lines in FIG. 5 to the solid line position. Cam lever 16 and piston rod 21 are not in vertical alignment so as to prevent interference therebetween. As the cam lever 16 is rotated in this manner, the cam follower 13a is caused to follow it by the biasing force of spring 15 thus opening the lower end of the chute 10. Accordingly, the lower most formed wire spring 1 rides on the inclined upper surface of the push up rod 13.

Before advancement of the spring feeding member 18, one of the formed wire springs I has already been dropped through the chute 9 and held by stop lever 24 at the discharge end-9a of the dropping chute 9. As the spring feeding member 18 is advanced, the magnet 19 attracts the formed wire spring for disengaging the spring from ledge 11a by opening stop lever 24. In this manner the formed wire spring 1 is transferred to the working station A.

Then the operation of the upper and lower twisting units 25 and 26 is commenced. Prior to this, of course the positions of the lock nuts 53 and 55 are adjusted to provide a desired twisting angle. In the modified embodiment shown in FIG. 6, a gauge 57 having a width corresponding to the desired twisting angle is selected. However, for the sake of simplicity, the description of the operation will be continued in connection with the embodiment shown in FIGS. 2 and 5.

By the concurrent operation of their pneumatic actuators spindles 31 and 32 are simultaneously advanced to the working station A to clamp a formed wire spring 1 between jaws 33 and 34 at the loop portion 2 thereof.

As has been pointed out hereinabove, the formed wire spring 1 is twisted at its torque bar portion 3. For the purpose of twisting this portion either one of the upper and lower jaws 33 and 34 is rotated by operating one of the pneumatic actuators of the twisting mechanism while the other jaw is being held stationary.

In the case shown in FIG. 3a, a particular torque bar portion 3a is twisted whereas in the case shown in FIG. 3b adjacent torque bar portion 311 is twisted. In both cases, the portions of the formed wire spring 1 to the right of the torque bar portion are bent in the same direction with respect to the portions of the formed wire spring 1 to the left of the torque bar. In the case shown in FIG.- 3a, the upper jaw 33 holds an upper loop portion 2a and the lower jaw 34 holds a lower loop portion 2b and then the upper jaw 33 is rotated in the direction indicated by an arrow while the lower jaw 34 is being held stationary. In the case shown in FIG. 3b, the upper jaw 33 holds an upper loop portion 36 and the lower jaw 34 holds a lower loop portion 2b and the lower jaw 34 is rotated in the direction shown by an arrow while the upper jaw 33 is being held stationary. It should be understood that in both cases, the portions of the formed wire spring I to the left of the twisted torque bar portion are held stationary by means of a suitable clamping device, not shown, for example, a magic hand of an automatic robot until completion of the twisting operation.

Generally, the formed wire spring has a large length and where the formed wire spring is to be twisted at a plurality of portions along the length thereof, the portions of the spring on one side of the twisting portion and having larger length than the portions on the opposite side are to be clamped as described above. For example, FIG. 4 shows a configuration of a formed wire spring which has already been twisted at various portions a through 11 inclusive in the following order. Thus, portions a and 11 near the opposite ends of the spring are firstly twisted, the twisting portions are then advanced toward the center and the middle portion e is finally twisted.

As described hereinabove, the twisting operation is performed by rotating either one of the upper and lower jaws by the associated twisting mechanism, and as is well known in the art the jaw is rotated over an angle slightly larger than the desired twisting angle by taking into consideration the resiliency or the tendency of spring back of the twisted spring 1.

Upon completion of the twisting operation, pressurized air is. discharged from one of the pneumatic actuators which has been operated for rotating one of the jaws 33 and 34. Then, the spring back force of the twisted spring 1 slightly rotates in the opposite direction the jaw that has been rotated for performing the twisting operation thereby loosely holding the spring 1. Thereafter, both spindles 31 and 32 are retracted away from the working station A to smoothly disengage the jaws 33 and 34 from the twisted spring 1. After completion of the twisting operation the finished formed wire spring 1 is conveyed to the left from the working station by said clamping device, not shown.

Then, the rack which has been advanced to rotate one of the jaws 33 and 34 is retracted by the associated pneumatic actuator thus returning the jaw to the original position.

The spring transfer member 181 which has been advanced for transferring a formed wire spring 1 to the working station A is retractedto the position shown in FIG. 2 by the pneumatic actuator associated therewith after the advanced spring 1 has held by the jaws 33 and 34. By the retracting motion of the spring transfer 7 through the dropping chute 9 by its own weight until it is arrested by lever 24 for use in the next cycle of the operation.

While in the foregoing description, the twisting operation performed at a single working station A has been described, where the twisting operation is performed at a plurality of portions along the length of a formed wire spring as shown in FIG. 4, while the spring is held at respective working stations by means of suitable clamping devices, the upper and lower twisting units 25 and 26 are moved from one working station to the other by sliding them along guide rails 27.

Either one of the right most position shown in FIG. 2 and the left most position may be used as the reference position of the racks 43 and 44 of the twisting units 25 and 26. Such selection can be readily made by the switching manually or solenoid operated valves, not shown, connected to the pneumatic actuators of the twisting mechanisms. By changing the reference positions of the racks, the directions of rotation of the jaws 33 and 34 are varied. Thus, the reference positions of the racks 43 and 44 are determined according to the direction of twisting.

The operations and timings of the various pneumatic actuators utilized in the twisting apparatus can be controlled by an automatic sequence control or manually.

Although the torque bar portions 3 of the formed wire springs l are usually twisted by the twisting apparatsu, loop positions 2 can also be twisted.

As has been described hereinabove, in accordance with this invention, the twisting devices are constructed as compact units of the same construction that can be moved to any desired working positions. For this reason, it is possible to twist the formed wire springs into any desired configurations suitable for use in various applications.

Moreover, as it is possible to readily vary the twisting angle by the twisting angle adjusting means, the preparation time before commencing the twisting operation can be greatly reduced, thus increasing the operational efficiency.

Further, the transfer mechanism operates to positively transfer the formed wire springs to the operating station, one after the other, thus assuring efficient twisting operations.

What is claimed is:

l. A twisting apparatus for twisting a formed wire' spring comprising:

a twisting unit disposed on one side of a working station, said twisting unit including:

a base block adjustable along a guide rail;

a spindle provided with a pinion at one portion thereof and slidably mounted on said base block;

a first pneumatic actuator disposed at one end of said spindle for moving said spindle in the axial direction;

a jaw mounted on the other end of said spindle, said jaw being adapted to clamp said formed wire spring upon operation of said first pneumatic actuator;

a rack disposed on said base block at right angles with respect to said spindle and arranged to drive said pinion;

a second pneumatic actuator for reciprocating said rack, thereby causing said jaw to rotate to twist said formed wire spring; and

adjusting means for adjusting the stroke of said rack, said adjusting means including a rod secured to one end of said rack, and a gauge member having a predetermined width and mounted on said rod between said one end of said rack and said base block.

2. A twisting apparatus according to claim 1, including a plurality of said gauge members having different widths, one of which is selectively mounted on said rod.

3. A twisting apparatus according to claim 1, wherein said gauge member includes a pair of arcuate halves and a hinge for connecting said arcuate halves together at their ends on one side.

4. A twisting apparatus according to claim 1, further comprising a transfer mechanism for transferring said formed wire spring to said working station, said transfer mechanism comprising:

spring guide plates which cooperate to define an inclined chute for accommodating a plurality of formed wire springs;

a dropping chute for dropping said springs to the discharge end of said dropping chute;

a vertical guide way interconnecting said inclined chute and said dropping chute;

a push up rod slidably received in said vertical guide way;

a spring transfer member slidable for transferring a formed wire spring at said discharge end of the dropping chute to said working station;

a third pneumatic actuator for slidably reciprocating said spring transfer member; and

means operated by the reciprocating sliding of said spring transfer member for reciprocating said push up rod in the vertical direction for transferring one by one said formed wire springs from said inclined chute to said dropping chute.

5. A twisting apparatus according to claim 4, wherein said spring transfer member includes a permanent magnet for attracting said formed wire spring. 

1. A twisting apparatus for twisting a formed wire spring comprising: a twisting unit disposed on one side of a working station, said twisting unit including: a base block adjustable along a guide rail; a spindle provided with a pinion at one portion thereof and slidably mounted on said base block; a first pneumatic actuator disposed at one end of said spindle for moving said spindle in the axial direction; a jaw mounted on the other end of said spindle, said jaw being adapted to clamp said formed wire spring upon operation of said first pneumatic actuator; a rack disposed on said base block at right angles with respect to said spindle and arranged to drive said pinion; a second pneumatic actuator for reciprocating said rack, thereby causing said jaw to rotate to twist said formed wire spring; and adjusting means for adjusting the stroke of said rack, said adjusting means including a rod secured to one end of said rack, and a gauge member having a predetermined width and mounted on said rod between said one end of said rack and said base block.
 2. A twisting apparatus according to claim 1, including a plurality of said gauge members having different widths, one of which is selectively mounted on said rod.
 3. A twisting apparatus according to claim 1, wherein said gauge member includes a pair of arcuate halves and a hinge for connecting said arcuate halves together at their ends on one side.
 4. A twisting apparatus according to claim 1, further comprising a transfer mechanism for transferring said formed wire spring to said working station, said transfer mechanism comprising: spring guide plates which cooperate to define an inclined chute for accommodating a plurality of formed wire springs; a dropping chute for dropping said springs to the discharge end of said dropping chute; a vertical guide way interconnecting said inclined chute and said dropping chute; a push up rod slidably received in said vertical guide way; a spring transfer member slidable for transferring a formed wire spring at said discharge end of the dropping chute to said working station; a third pneumatic actuator for slidably reciprocating said spring transfer member; and means operated by the reciprocating sliding of said spring transfer member for reciprocating said push up rod in the vertical direction for transferring one by one said formed wire springs from said inclined chute to said dropping chute.
 5. A twisting apparatus according to claim 4, wherein said spring transfer member includes a permanent magnet for attracting said formed wire spring. 